A comparison of conventional microspectrophotometry and hyperspectral imaging for the analysis of blue metallic paint samples

Paint is often encountered as forensic evidence, particularly in cases involving vehicle accidents or property damage. In a forensic context, visual examination and color analysis of paint samples are methods employed early in the analytical sequence. Conventional visible microspectrophotometry, a technique dating back to the l980s, is a well-documented analytical technique for forensic analysis. Hyperspectral imaging, on the other hand, is a relatively new technique with many potential forensic applications yet to he fully explored. In this pilot study, hyperspectral imaging using the Prism and Reflector Imaging Spectroscopy System (PARISS) and associated software was applied to a range of metallic blue vehicle paint samples, and the results were compared with those obtained using conventional microspectrophotometry. The results suggest that hyperspectral imaging offers significant advantages, particularly for heterogeneous samples such as metallic paint where conventional microspectrophotometry is problematic. The PARISS generated high-quality spectra and a high level of discrimination, with additional advantages that included individualized spectral libraries, result histograms and false-color images showing the distribution of spectral types across a sample. Although only a preliminary investigation has been conducted on a limited set of blue metallic samples (flat and relatively large in size), the superior discriminating power combined with the rapid generation of spectra across the field of view suggests that hyperspectral imaging using the PARISS may be an efficient and effective alternative to traditional microspectrophotometry for the analysis of vehicle paints. The results justify further research to explore the application of hyperspectral imaging as an alternative to conventional microspectrophotometry